When you're flying these days, you'll usually hear the flight crew instruct you during takeoff and landing to turn off "any device that has an off button"—not just activating airplane mode, but physically turning off the device. This makes very little sense to most tech-savvy types, but James Fallows at The Atlantic has a few theories on the seemingly arbitrary rule. One is that the pilot and crew need your attention, in case something goes wrong. The other theories revolve around the actual devices: their capabilities for interference, and their likelihood of annoying other passengers.

If this were the case, wouldn't we tell people not to have books, magazines, newspapers and crossword puzzles during this critical part of a flight? Also, we don't ask passengers on other forms of public transportation, including buses, trains, boats and cars — where far more accidents happen than planes — to shut down their iPhones or iPads when the vehicle begins moving. Should we tell people they can't sleep during this time either in case something happens?

What's your best guess as to why you can't use any device, no matter how innocuous, during takeoff and landing? Do you respect the call for powering down? Photo by Global X.